E-50The E-50 was planned as successor to the Panther and the Panther II (which never went beyond prototype status). By 1945 the E-50 existed only on paper. Its main gun would have been the same 88mm canon that had been used for the Königstiger. The main goal of the E-series was to create as many parts as possible that were interchangeable between the series-tanks and thus make spare parts supply easier.